Simplify locking process for VM migration
Rather than using a cumbersome and overly complex ping-pong of read and write locks, instead move to a much simpler process using exclusive locks. Describing the process in ASCII or narrative is cumbersome, but the process ping-pongs via a set of exclusive locks and wait timers, so that the two sides are able to synchronize via blocking the exclusive lock. The end result is a much more streamlined migration (takes about half the time all things considered) which should be less error-prone.
This commit is contained in:
parent
16c38da5ef
commit
341073521b
|
|
@ -425,42 +425,12 @@ class VMInstance(object):
|
|||
migrate_lock_node.acquire()
|
||||
migrate_lock_state.acquire()
|
||||
|
||||
time.sleep(0.2) # Initial delay for the first writer to grab the lock
|
||||
|
||||
# Don't try to migrate a node to itself, set back to start
|
||||
if self.node == self.lastnode or self.node == self.this_node.name:
|
||||
abort_migrate('Target node matches the current active node during initial check')
|
||||
return
|
||||
|
||||
# Synchronize nodes A (I am reader)
|
||||
lock = self.zkhandler.readlock(('domain.migrate.sync_lock', self.domuuid))
|
||||
self.logger.out('Acquiring read lock for synchronization phase A', state='i', prefix='Domain {}'.format(self.domuuid))
|
||||
lock.acquire()
|
||||
self.logger.out('Acquired read lock for synchronization phase A', state='o', prefix='Domain {}'.format(self.domuuid))
|
||||
if self.zkhandler.read(('domain.migrate.sync_lock', self.domuuid)) == '':
|
||||
self.logger.out('Waiting for peer', state='i', prefix='Domain {}'.format(self.domuuid))
|
||||
ticks = 0
|
||||
while self.zkhandler.read(('domain.migrate.sync_lock', self.domuuid)) == '':
|
||||
time.sleep(0.1)
|
||||
ticks += 1
|
||||
if ticks > 300:
|
||||
self.logger.out('Timed out waiting 30s for peer', state='e', prefix='Domain {}'.format(self.domuuid))
|
||||
aborted = True
|
||||
break
|
||||
self.logger.out('Releasing read lock for synchronization phase A', state='i', prefix='Domain {}'.format(self.domuuid))
|
||||
lock.release()
|
||||
self.logger.out('Released read lock for synchronization phase A', state='o', prefix='Domain {}'.format(self.domuuid))
|
||||
|
||||
if aborted:
|
||||
abort_migrate('Timed out waiting for peer')
|
||||
return
|
||||
|
||||
# Synchronize nodes B (I am writer)
|
||||
lock = self.zkhandler.writelock(('domain.migrate.sync_lock', self.domuuid))
|
||||
self.logger.out('Acquiring write lock for synchronization phase B', state='i', prefix='Domain {}'.format(self.domuuid))
|
||||
lock.acquire()
|
||||
self.logger.out('Acquired write lock for synchronization phase B', state='o', prefix='Domain {}'.format(self.domuuid))
|
||||
time.sleep(0.5) # Time for reader to acquire the lock
|
||||
time.sleep(0.5) # Initial delay for the first writer to grab the lock
|
||||
|
||||
def migrate_live():
|
||||
self.logger.out('Setting up live migration', state='i', prefix='Domain {}'.format(self.domuuid))
|
||||
|
|
@ -500,9 +470,14 @@ class VMInstance(object):
|
|||
self.shutdown_vm()
|
||||
return True
|
||||
|
||||
do_migrate_shutdown = False
|
||||
self.logger.out('Acquiring lock for phase B', state='i')
|
||||
lock = self.zkhandler.exclusivelock(('domain.migrate.sync_lock', self.domuuid))
|
||||
try:
|
||||
lock.acquire(timeout=30.0)
|
||||
except Exception:
|
||||
abort_migrate('Timed out waiting for peer')
|
||||
return
|
||||
migrate_live_result = False
|
||||
|
||||
# Do a final verification
|
||||
if self.node == self.lastnode or self.node == self.this_node.name:
|
||||
abort_migrate('Target node matches the current active node during final check')
|
||||
|
|
@ -510,7 +485,6 @@ class VMInstance(object):
|
|||
if self.node != target_node:
|
||||
abort_migrate('Target node changed during preparation')
|
||||
return
|
||||
|
||||
if not force_shutdown:
|
||||
# A live migrate is attemped 3 times in succession
|
||||
ticks = 0
|
||||
|
|
@ -525,59 +499,27 @@ class VMInstance(object):
|
|||
break
|
||||
else:
|
||||
migrate_live_result = False
|
||||
|
||||
if not migrate_live_result:
|
||||
if force_live:
|
||||
self.logger.out('Could not live migrate VM while live migration enforced', state='e', prefix='Domain {}'.format(self.domuuid))
|
||||
aborted = True
|
||||
else:
|
||||
do_migrate_shutdown = True
|
||||
|
||||
self.logger.out('Releasing write lock for synchronization phase B', state='i', prefix='Domain {}'.format(self.domuuid))
|
||||
migrate_shutdown()
|
||||
lock.release()
|
||||
self.logger.out('Released write lock for synchronization phase B', state='o', prefix='Domain {}'.format(self.domuuid))
|
||||
|
||||
if aborted:
|
||||
abort_migrate('Live migration failed and is required')
|
||||
return
|
||||
|
||||
# Synchronize nodes C (I am writer)
|
||||
lock = self.zkhandler.writelock(('domain.migrate.sync_lock', self.domuuid))
|
||||
self.logger.out('Acquiring write lock for synchronization phase C', state='i', prefix='Domain {}'.format(self.domuuid))
|
||||
time.sleep(0.5)
|
||||
|
||||
self.logger.out('Acquiring lock for phase D', state='i')
|
||||
lock.acquire()
|
||||
self.logger.out('Acquired write lock for synchronization phase C', state='o', prefix='Domain {}'.format(self.domuuid))
|
||||
time.sleep(0.5) # Time for reader to acquire the lock
|
||||
|
||||
if do_migrate_shutdown:
|
||||
migrate_shutdown()
|
||||
|
||||
self.logger.out('Releasing write lock for synchronization phase C', state='i', prefix='Domain {}'.format(self.domuuid))
|
||||
lock.release()
|
||||
self.logger.out('Released write lock for synchronization phase C', state='o', prefix='Domain {}'.format(self.domuuid))
|
||||
|
||||
# Synchronize nodes D (I am reader)
|
||||
lock = self.zkhandler.readlock(('domain.migrate.sync_lock', self.domuuid))
|
||||
self.logger.out('Acquiring read lock for synchronization phase D', state='i', prefix='Domain {}'.format(self.domuuid))
|
||||
lock.acquire()
|
||||
self.logger.out('Acquired read lock for synchronization phase D', state='o', prefix='Domain {}'.format(self.domuuid))
|
||||
|
||||
self.last_currentnode = self.zkhandler.read(('domain.node', self.domuuid))
|
||||
self.last_lastnode = self.zkhandler.read(('domain.last_node', self.domuuid))
|
||||
|
||||
self.logger.out('Releasing read lock for synchronization phase D', state='i', prefix='Domain {}'.format(self.domuuid))
|
||||
lock.release()
|
||||
self.logger.out('Released read lock for synchronization phase D', state='o', prefix='Domain {}'.format(self.domuuid))
|
||||
|
||||
# Wait for the receive side to complete before we declare all-done and release locks
|
||||
ticks = 0
|
||||
while self.zkhandler.read(('domain.migrate.sync_lock', self.domuuid)) != '':
|
||||
time.sleep(0.1)
|
||||
ticks += 1
|
||||
if ticks > 100:
|
||||
self.logger.out('Sync lock clear exceeded 10s timeout, continuing', state='w', prefix='Domain {}'.format(self.domuuid))
|
||||
break
|
||||
migrate_lock_node.release()
|
||||
migrate_lock_state.release()
|
||||
lock.release()
|
||||
|
||||
self.inmigrate = False
|
||||
return
|
||||
|
|
@ -592,55 +534,37 @@ class VMInstance(object):
|
|||
|
||||
self.logger.out('Receiving VM migration from node "{}"'.format(self.last_currentnode), state='i', prefix='Domain {}'.format(self.domuuid))
|
||||
|
||||
# Short delay to ensure sender is in sync
|
||||
time.sleep(0.5)
|
||||
|
||||
# Ensure our lock key is populated
|
||||
self.zkhandler.write([
|
||||
(('domain.migrate.sync_lock', self.domuuid), self.domuuid)
|
||||
])
|
||||
|
||||
# Synchronize nodes A (I am writer)
|
||||
lock = self.zkhandler.writelock(('domain.migrate.sync_lock', self.domuuid))
|
||||
self.logger.out('Acquiring write lock for synchronization phase A', state='i', prefix='Domain {}'.format(self.domuuid))
|
||||
lock.acquire()
|
||||
self.logger.out('Acquired write lock for synchronization phase A', state='o', prefix='Domain {}'.format(self.domuuid))
|
||||
time.sleep(1) # Time for reader to acquire the lock
|
||||
self.logger.out('Releasing write lock for synchronization phase A', state='i', prefix='Domain {}'.format(self.domuuid))
|
||||
self.logger.out('Acquiring lock for phase A', state='i')
|
||||
lock = self.zkhandler.exclusivelock(('domain.migrate.sync_lock', self.domuuid))
|
||||
try:
|
||||
lock.acquire(timeout=30.0)
|
||||
except Exception:
|
||||
self.logger.out('Failed to acquire exclusive lock for VM', state='w')
|
||||
return
|
||||
# Exactly twice the amount of time that the other side is waiting
|
||||
time.sleep(1)
|
||||
lock.release()
|
||||
self.logger.out('Released write lock for synchronization phase A', state='o', prefix='Domain {}'.format(self.domuuid))
|
||||
time.sleep(0.1) # Time for new writer to acquire the lock
|
||||
|
||||
# Synchronize nodes B (I am reader)
|
||||
lock = self.zkhandler.readlock(('domain.migrate.sync_lock', self.domuuid))
|
||||
self.logger.out('Acquiring read lock for synchronization phase B', state='i', prefix='Domain {}'.format(self.domuuid))
|
||||
time.sleep(0.5)
|
||||
|
||||
self.logger.out('Acquiring lock for phase C', state='i')
|
||||
lock.acquire()
|
||||
self.logger.out('Acquired read lock for synchronization phase B', state='o', prefix='Domain {}'.format(self.domuuid))
|
||||
self.logger.out('Releasing read lock for synchronization phase B', state='i', prefix='Domain {}'.format(self.domuuid))
|
||||
# This is strictly a synchrozing step
|
||||
time.sleep(0.1)
|
||||
lock.release()
|
||||
self.logger.out('Released read lock for synchronization phase B', state='o', prefix='Domain {}'.format(self.domuuid))
|
||||
|
||||
# Synchronize nodes C (I am reader)
|
||||
lock = self.zkhandler.readlock(('domain.migrate.sync_lock', self.domuuid))
|
||||
self.logger.out('Acquiring read lock for synchronization phase C', state='i', prefix='Domain {}'.format(self.domuuid))
|
||||
time.sleep(0.5)
|
||||
|
||||
self.logger.out('Acquiring lock for phase E', state='i')
|
||||
lock.acquire()
|
||||
self.logger.out('Acquired read lock for synchronization phase C', state='o', prefix='Domain {}'.format(self.domuuid))
|
||||
|
||||
# Set the updated data
|
||||
self.last_currentnode = self.zkhandler.read(('domain.node', self.domuuid))
|
||||
self.last_lastnode = self.zkhandler.read(('domain.last_node', self.domuuid))
|
||||
|
||||
self.logger.out('Releasing read lock for synchronization phase C', state='i', prefix='Domain {}'.format(self.domuuid))
|
||||
lock.release()
|
||||
self.logger.out('Released read lock for synchronization phase C', state='o', prefix='Domain {}'.format(self.domuuid))
|
||||
|
||||
# Synchronize nodes D (I am writer)
|
||||
lock = self.zkhandler.writelock(('domain.migrate.sync_lock', self.domuuid))
|
||||
self.logger.out('Acquiring write lock for synchronization phase D', state='i', prefix='Domain {}'.format(self.domuuid))
|
||||
lock.acquire()
|
||||
self.logger.out('Acquired write lock for synchronization phase D', state='o', prefix='Domain {}'.format(self.domuuid))
|
||||
time.sleep(0.5) # Time for reader to acquire the lock
|
||||
|
||||
self.state = self.zkhandler.read(('domain.state', self.domuuid))
|
||||
self.dom = self.lookupByUUID(self.domuuid)
|
||||
if self.dom:
|
||||
|
|
@ -672,10 +596,7 @@ class VMInstance(object):
|
|||
else:
|
||||
# The send failed or was aborted
|
||||
self.logger.out('Migrate aborted or failed; VM in state {}'.format(self.state), state='w', prefix='Domain {}'.format(self.domuuid))
|
||||
|
||||
self.logger.out('Releasing write lock for synchronization phase D', state='i', prefix='Domain {}'.format(self.domuuid))
|
||||
lock.release()
|
||||
self.logger.out('Released write lock for synchronization phase D', state='o', prefix='Domain {}'.format(self.domuuid))
|
||||
|
||||
self.zkhandler.write([
|
||||
(('domain.migrate.sync_lock', self.domuuid), '')
|
||||
|
|
|
|||
Loading…
Reference in New Issue